Among devices driven by batteries, especially mobile information devices such as portable telephones and personal information management (PIM) devices, there are devices which inform a user of incoming calls through bodily sensation by the vibration of an electromagnetic vibrator incorporated in the device.
A widely used vibrating method uses an electromagnetic vibrator as a drive for cost and energy efficiency reasons. Some electromagnetic vibrators contain a rotation-vibration structure in which an eccentric weight is attached to a motor while others have a reciprocating-vibration structure such as a speaker.
As a method of fixing the electromagnetic vibrator to the device, in most of the cases, one of the following methods is adopted. One method uses screws to fix the electromagnetic vibrator firmly to the device. In the other method, the electromagnetic vibrator is inserted into the device via an elastic body. With the latter method, the electromagnetic vibrator can be protected from impact caused when the device is accidentally dropped. Furthermore, since there is an elastic body, its cushioning function provides a shock absorbing effect to the whole body of the device itself. For these reasons the latter method is more widely used.
The main components to be incorporated into a portable device of this kind, are a button battery, electronic components and an electromagnetic vibrator. Common electric connection methods between those components and the device include the following.
The first method is used when incorporating the button battery into the device. A structure in which a flat spring protruding from the device contacts elastically an electrode of the button battery, is adopted so that the button battery can be easily placed and removed. The next method is used when mounting electronic components on a printed circuit board. In this case, the electronic components are mounted by reflow-soldering.
A conventional method used when incorporating the electromagnetic vibrator into the device is described as follows. FIG. 8 shows a side view of a conventional mounting structure of a motor functioning as an electromagnetic vibrator incorporated into the device.
In FIG. 8, a slim cylindrical motor 151 functioning as an electromagnetic vibrator has a case 153. One end of the output shaft of the motor 151 protrudes out of the case 153. The tip of the shaft is provided with an eccentric weight 200. With the rotation of the motor 151, the eccentric weight 200 rotates generating vibration.
The case 153 of the motor 151 is covered with a boot 155 made of synthetic rubber, and is placed between a mounting plate 161 and a housing 162 of the device.
Conventionally, in the case of the motor 151 which is elastically disposed in the above-mentioned manner, a lead line 154 for supplying electricity to the motor 151 is connected by soldering considering the reliability.
However, in recent years, there has been increasing demand for an improved productivity by using automatic assembling machine to facilitate incorporation of the electromagnetic vibrator into the device. To respond to such demand, when incorporating the electromagnetic vibrator into the device, the method used when incorporating a button battery into the device, has come to be adopted. That is, an elastically-connected electric connection structure has been more widely used. One of the related prior arts was disclosed in Japanese Patent Application Unexamined Publication No. H08-308170.
FIG. 9 shows a perspective view of a conventional mounting structure of a motor to the device.
In FIG. 9, an eccentric weight 192 is attached to a rotation shaft of a slim cylindrical motor 181. The motor 181 and the eccentric weight 182 constitute the electromagnetic vibrator. A case 183 of the motor 181 is fixed to a mounting board 191 by elastic holders 192. Electrodes (not illustrated) which connect inside of the motor, are formed on one end of the case 183. Elastic holders 193 protrude from the mounting board 191. The electrode mentioned above contact with a pair of holders 193. The device and the motor 181 are electrically connected by the holders 193 to supply electricity to the motor 181. With this construction, the motor 181 is fixed to the mounting board 191 as firmly as being screwed. Furthermore, the motor 181 can easily be incorporated into the device, and the electric connection is secured.
However, this conventional construction can not be adopted to the case in which a motor functioning as an electromagnetic vibrator is incorporated into the device while holding the motor elastically. Providing the conventional construction is adopted, if the motor being held elastically is incorporated into the device, a contact failure would possibly occur due to the sliding of the electric connection caused by vibration. This possibility is also mentioned in H08-308170.
In the technical field of the present invention, as FIG. 9 illustrates, reliability of the electric connections provided through the elastic contact could be maintained if the electromagnetic vibrator is firmly fixed to the device. However, when the electromagnetic vibrator held elastically is incorporated into the device, the reliability of the elastically contacting section can not be maintained, if the electric connection is provided through the elastic contact. In other words, there is an antinomy relationship between incorporating the electromagnetic vibrator, held elastically into the device and providing the electric connection through elastic contact.
In order to hold the electromagnetic vibrator elastically, the elastically contacted portion needs to resist the external impact. However, such impact resistance has been difficult to achieve in the technology field of the present invention where components are very small.